Ensure translations are loaded.

Since i18next loads translations asynchronously we need to make sure
that they are loaded before we call the JS code which depends on them.

Fixes #982

static/js/src/main.js

@@ -1,26 +1,45 @@
 // commonjs code goes here
 
-var i18n = window.i18n = require('i18next');
-var XHR = require('i18next-xhr-backend');
-var lngDetector = require('i18next-browser-languagedetector');
-var backendOptions = {
-    loadPath: '/static/locale/__lng__/translations.json'
-};
+(function () {
+    var i18n = window.i18n = require('i18next');
+    var XHR = require('i18next-xhr-backend');
+    var lngDetector = require('i18next-browser-languagedetector');
+    var backendOptions = {
+        loadPath: '/static/locale/__lng__/translations.json'
+    };
+    var callbacks = [];
+    var initialized = false;
 
-var detectionOptions = {
-    order: ['htmlTag'],
-    htmlTag: document.documentElement
-};
+    var detectionOptions = {
+        order: ['htmlTag'],
+        htmlTag: document.documentElement
+    };
 
-i18n.use(XHR)
-    .use(lngDetector)
-    .init({
-        nsSeparator: false,
-        keySeparator: false,
-        interpolation: {
-            prefix: "__",
-            suffix: "__"
-        },
-        backend: backendOptions,
-        detection: detectionOptions
-});
+    i18n.use(XHR)
+        .use(lngDetector)
+        .init({
+            nsSeparator: false,
+            keySeparator: false,
+            interpolation: {
+                prefix: "__",
+                suffix: "__"
+            },
+            backend: backendOptions,
+            detection: detectionOptions
+        }, function () {
+            var i;
+            initialized = true;
+            for (i=0; i<callbacks.length; i++) {
+                callbacks[i]();
+            }
+        });
+
+    i18n.ensure_i18n = function (callback) {
+        if (initialized) {
+            callback();
+        } else {
+            callbacks.push(callback);
+        }
+    };
+
+}());